Generate the Sequence number whenever I click on SUbmit Button to the below code

body {
background: url(bg.jpg);
}
#formdiv {
border: solid 2px #b7ddf2;
background: #aaaaaaa;
width:650px;
height:550px;
-moz-border-radius:15px;
-webkit-border-radius:5px;
}

#formdiv h2 {
font-size: 25px;
font-weight: bold;
text-align:center;
color: #2A1F55;
margin-bottom: 8px;
}

#formdiv p {
font-size: 13px;
color: #2A0000;
margin-bottom: 20px;
border-bottom: solid 1px #2A1F55;
padding-bottom: 10px;
}

#formdiv label {
display: block;
font-weight: bold;
color:#2A1F00;
text-align: right;
width: 100px;
float: left;
}

#formdiv input {
float: left;
font-size: 10px;
background-color: #F5F5F5;
padding: 4px 2px;
border: solid 1px #80764D;
width: 200px;
margin: 2px 0 20px 10px;
-moz-border-radius:5px;
-webkit-border-radius:2px;
}
#formdiv button {
clear: both;
margin-left: 20px;
width: 100px;
height: 30px;
background: #1E90FF;
text-align: center;
color: #FFFFFF;
font-size: 11px;
font-weight: bold;
-moz-border-radius:5px;
-webkit-border-radius:2px;
}


This is the CSS code for the folowinf HTML Code ...
Now my question After clicking on submit button I need to generate a Sequence number whenever we click on submit and all details will be stores in table along with that sequence number

 

And for that you create an id-field in the table with autoincrement, and the sequencenumber will be taken care of by the database.